The present invention relates in general to network-based voice communications, and more particularly to a system for transporting DPNSS (Digital Private Signaling System) signaling and voice using Internet Protocol (IP).
As set forth in BTNR 188 Digital Private Network Signaling System (DPNSS), the DPNSS standard defines three interface layers: the physical layer, the link layer and the network layer. The physical layer can be implemented on an E1 or T1 digital trunk and provides physical transport for voice and signaling. The link layer defined in the standard provides reliable transport for signaling information and requires a 64 Kbps channel using HDLC framing. The network layer defines the signaling data and deals with call establishment, calling information, call clearing and call feature transparency between network nodes. It is supported within the Call Control Software of a Telecoms Server.
Traditionally DPNSS has been transported over a TDM (Time Division Multiplexing) infrastructure that is E1 (or T1) based. This has required separate voice and data wiring which contributes to system cost. Another limitation of E1 trunks using DPNSS is that E1 (or T1) trunks provide a point to point connection. All 30 channels within an E1 link are required to terminate between the same network nodes.
According to the present invention, a system is provided for implementing the DPNSS protocol and voice transport over IP (Internet Protocol). A principal benefit of the system according to the present invention is that it is possible to use the existing data wiring infrastructure of a LAN (Local Area Network). In many situations this eliminates the need for a separate transport infrastructure which reduces the customer""s monthly recurring charges of a leased trunk service. Also, because IP is a switched service each trunk can be individually programmed to terminate between two network nodes. In addition, the signaling information associated with the trunk is routed over the network. This provides more flexibility and better utilization of trunk resources than prior art E1 and T1 based systems.